Moving window display for Landsat 8

March 17th, 2014, Published in Articles: PositionIT

 

by Riaan Stegmann, SANSA Earth Observation

Late last year SANSA Earth Observation became one of the first ground stations in the world to acquire a moving window display for Landsat 8. Landsat 8 images are used by the departments of agriculture, water affairs, environmental affairs, and rural development and land reform, as well as the CSIR, the National Housing Agency (NHA), Eskom and GeoTerraImage (GTI), amongst others, in the planning and execution of their operations.

The moving window display, developed by the Pinkmatter company in Pretoria, is a visual representation of a satellite pass over the footprint area commonly referred to as a pass. This display aids technical operators who monitor the pass in order to validate the quality of a pass while the satellite imagery is being downloaded. One of the possible problems encountered could be brief losses in signal due to interference.

Fig. 1: Visual representation of the tracks of Landsat 8 (left) and Landsat 7 (right).

Fig. 1: Visual representation of the tracks of Landsat 8 (left) and Landsat 7 (right).

Using the moving window display, operators are now able to pinpoint the current position of Landsat 7 and Landsat 8 satellites as they move along their orbit in space. Each pass is recorded and stored in an internal database, which can be replayed at any given time afterwards.

Fig. 2: Current imagery coming from the satellite as it passes can be displayed in true colour, natural false colour and vegetation false colour.

Fig. 2: Current imagery coming from the satellite as it passes can be displayed in true colour, natural false colour and vegetation false colour.

As soon as a pass starts, the display changes to reflect the current imagery coming down from the satellite. This is accompanied by information about the current pass on the right hand side of the screen which reflects the related information as well as a visual representation of the track the satellite is currently following.

Fig. 3: Information about the current pass is displayed in the right side panel, along with previously recorded data which can be replayed.

Fig. 3: Information about the current pass is displayed in the right side panel, along with previously recorded data which can be replayed.

One could also change the bands to one of three pre-sets including:

  • True colour (default)
  • Natural false colour
  • Vegetation false colour

With the addition of the Landsat moving window display, SANSA has moved a step closer to becoming one of the world’s foremost authorities on technology in the field of earth observation.

The United states Geological Survey (USGS) jointly manages the Landsat 8 satellite in conjunction with NASA. Landsat 8 provides a clearer view as it carries two highly-sensitive observation instruments, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). This advanced technology increases the reliability and sensitivity of these instruments, while the improved measurements are still compatible with the past Landsat data record.

The earth observation community in South Africa will now be able to access Landsat data within a few hours of acquisition giving rapid access to acquired data. The same geographic location is imaged (also known as the repeat cycle) every 16 days and this is useful for agricultural crop monitoring, forests, water and other applications.

Contact Jane Olwoch, SANSA, Tel 012 844-0385, jolwoch@sansa.org.za

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